


I'll teach you to love me

by orphan_account



Category: Undertale
Genre: Alternate Universe - Underswap, Big Brother Papyrus, Brother/Brother Incest, Chloroform, Date Rape Drug/Roofies, Drugs, Drunk Sex, Drunk rape, Killing, M/M, Murder, One-Sided Attraction, One-Sided Relationship, Other, Pain, Sibling Incest, Torture, Unconditional Love, Underswap Muffet, Underswap Papyrus, Underswap Sans, Yandere Sans, Yandere!Underswap!Sans, binding, blowjob, sobbing papy
Language: English
Status: In-Progress
Published: 2016-10-31
Updated: 2016-11-04
Packaged: 2018-08-28 04:06:09
Rating: Explicit
Warnings: Graphic Depictions Of Violence, Major Character Death, Rape/Non-Con
Chapters: 2
Words: 2,080
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8431237
Author URL: https://archiveofourown.org/users/orphan_account/pseuds/orphan_account
Summary: Sans finally gets the courage to tell his love he wants to be with him. But when he rejects. Being his brother and in love with a certain robot. Sans goes a little haywire.





	1. Chapter 1

**Author's Note:**

> AAUUH I got into yandere Sans everyone B)

Sans stood by puzzles he had recalibrated. Saying ever so slightly. Today was the day! The love of his life would learn of his affections. A purr leaving his teeth as he thought of them. Getting married, kissing, _fucking_. People thought Sans was oh so INNOCENT. But he really weren't. Sans basked in the time he found shit online, so glad he came across such amazing sexual fetishes and kinks.

Giggling as he crunched his blue heeled boots into the soft snow under him. Moving to the direction if his lovely home snowdin. Waving to the dogs he walked by. His usual trot and happy innocent demeanor gleaming with happiness. Getting to the warmth of his house was enough to make him shake with glee. Stomping the snow off. "Papy~? You home??" No reply...

Good. Making his way up the wooden stairs. Creaking along the way; hot and bothered from his thoughts earlier. The small blueberry like sans made his way into his brothers room. Looking around. Papyrus wasn't here. Good good good. Perking as he entered. Flopping onto the bed shuffling from his pants. Circling a soft finger around his pelvis.

"Oh papy" a purr is muttered. Magic forming into the slick vagina he wished his brother could plow into. He removed a dildo he had watched papyrus use once when he was younger. Being short made for an amazing hidder.

Carefully moving it. It was unlearned and used way to often. But sans didn't care. Just wanted the amazing knowledge that his beautiful older brother had used this shafted item. Lowering onto it. It was smaller then papyrus. But it would have to do.

As he bounced and moaned, his wet entrance being used for the second time today for this. Imagine his brothers long fabulous length. Sans used to hide under an old desk papyrus bad. He'd watched him Jack off so often, occasionally snapping photos. Oh but those photos edged him on.

Sans gasp as his hips shuttered. A moan leaving him when he clenched and groaned. Spasming around the toy. Continuing to bounce in his orgasm. Biting a finger as he slid off and re-inventoried it. Moving so nothing could leak on the bed. Pulling the pants upward, magic dissipating.

Leaving the room and making it to his adorable room. A galaxy rug. The most comfortable rocket ship bed with- the ceiling covered in glow in the dark stick-on stars. A computer in the corner with a blue and purple desk. Azure book shelves holding magazines and books of all kinds. 

The table if action figures and stuffed animals. And not to mention a box filled with the attacks sans would use on a person some day. Humming as he trotted in. Going to his closet. The closet was covered wall to wall in pictures of papyrus. Hearts surrounding the interior.

"Oh papyrus. I'll tell you today!! We can be forever together. W-we don't need anyone but us~" he kissed the pictures. Hearing the door open downstairs. He wafting smell of smoke nearly immediately staining the house.

Sans stands, immediately sauntering out of the closet. Locking it and running down stairs. "Papyrus!!"

"Oh hello bro, whatcha up to? Thought you'd be at Alphys's today" the tall skeleton huffed out a puff of smoke. 

Sans shifted. Grabbing his brothers arm and leading him to the couch. "I- cancelled. I need to talk to you" he said very enthusiastically. But Papyrus seemed a bit worried as they both sat.

"Uh. Yeah? Lay it on me Sansy" that nickname made sans shiver. He took papyrus's and began.

"W-well pap. I--I'm in love with you"

"I love you too bro-"

"No-no I mean. I want to kiss you and stuff and and be together forever" seeing his face drop made sans shake. Tightly holding the grip on the others hand. "And and I'd. I'd even let you fu-fuck me and hold me we-we'd get married and-" a hand was brought off. Pushing him away slightly 

Prying his tight grip off. His head shaking rapidly. "N-no sans we're-,""I KNOW WE'RE BROTHERS!! But I don't care papyrus please-"

"No. Sans. We.... that's not normal you. You need help sans you're not supposed to feel this for me. Ob-obviously you need to talk to someone"

Sans was shaking. His worked crashing as he went on. He'd make him see undyne twice a week to 'talk' about this PROBLEM. It wasn't a problem. It wasn't. "And I love...I love Napstaton-you-" sans stood. Trembling. He'd never felt so awful. Papyrus grabbed his shoulders. Panic coursing through.

'You'll get him. You'll make him love you...'

~~~

It had been two weeks. Seeing undyne. She explained. Sans only felt this way because his lack of long-term friends. And that naturally his body and mind must've shifting to a false love for a family member. But his love burned true. Wanting to be with his brother was the only thing he'd EVER. Wanted. As soon as sans felt the ability to love he knew. He knew papy was the one.

Papyrus meanwhile. Had spent even more time with that stupid. Ugly robot. Someone sans had once looked up to had easily been flipped into an enemy. Mortal. Every one had heard about the therapy like sessions. People who had made fun of Sans when he was young spread rumors like wildfire.

"I knew he was fucked up"

"Messed up bitch"

"Mentally disturbed"

 

It erked him. Knowing he had been rejected. But he had a plan. Sitting in and listening to undyne talk about symptoms of some thing he hadn't cared for. Looking up.

Sniffling lightly. Sans wiped a fake tear. "Can I...get a hug" undyne shyly walked over. Bending down to his height. Sans wrapped hands around her. Holding the shy fish close. A bone appearing in his hands.

"Tibia-honest...it's ridiculous you tried to help at all. You just want us to be SEPARATED for your robotic whore"

Immediately the bone stabbed into the fish. More appearing in it's place. A mouth covering the fishes mouth. She screamed muffled cried as he hp was deeply drained.

He watched her body fizzle into soft powdery dust. EXP running into Sans. Even raising a level. The feeling was like none like he'd ever felt. It was...amazing...almost...addicting.

"Papyrus is mine. And only mine..." with that sans quickly swept the dust. Tossing it into the trash where it belonged. Getting rid of the clothing quickly as he gathered items. Making a makeshift holding chair and keeping it there. Running out. He'd called Napstaton. Letting the robot be trapped...

He typed the number in. Bringing it to his face.

"Hello rad-boy NTT here?"

"Hello ? It's sans... Undyne wants you to come over if that's quite alright?"

"Oh it's fine!! I'll be there in a jiffy bruh" they hung up. Great. Hoping papyrus wouldn't stop them. Sans waited about 20 God damn minutes.  
Waiting by the door in the dark.

It slides open. The robot clanking in. Adjusting their Hat. "Hey? Sans? Undyne?"

Sans raised a pipe he'd ripped off of somewhere. Slamming it against the robots head. They collapsed. Confused as they let out a scream. They hit them multiple times. Using bones to cause their battery to disperse. He drags the body so it turns around. The robot whining and attempting to weakly tear sans off of him. 

"Papyrus is mine. NTT. I used to love you too" he mercilessly began to bash their fake skull in. As well as ripping the soul from the case on the chest. Crushing it. More LOVE and EXP filling him. It felt so g o o d.

Next was papyrus....

He folded the made chair. Luckily reading all those trap books made it was much easier to make amazing items. Sans inventoried it. It was heavy but he managed. Quickly making his way home to wait for papyrus. Making sure to hide the robotic pieces. Keeping an arm as a trophy.

Papy. Sans is on his way.

Sans made it home. Luckily papyrus was probably. And hopefully getting wasted at Muffets, going upstairs and dropping the chair down. Huffing as he unfolded it. Giggling and clapping. He made a nice heart around it with rose petals. Candles scented with amazing assorted smells lighted around. Even opening the closet so all the pictures were seen. 

Taking some and placing them around. The robot arm placed on the desk. Blue waiting downstairs for his amazing fantastic and HIS brother...


	2. My brother my lover

**Summary for the Chapter:**

> Blue gets his brother.
> 
> contains an alcohol blowjob (noncon)
> 
> Short bc I have a hangover

(PAPYS POV)

Papyrus yawns. Stepping out of Undynes lab. Waving goodbye to her and his brother. He walked through lands and sighed. The day his little brother confessed to being in love with him was stressful. He had cried so hard. Papyrus felt completely awful but. He did not find it right. He could never love his brother that way.

Just thinking of it made him sick. Only sickos wanted to be with their brothers, for brothers to be together (;y). It wasn't Sans's fault. It can't be! He was a lonely child. He never had any friends of course his mind would trick him like that!

Sighing as he shuffled through snowdin. Moving to Muffets. He was savage there. Well felt safe; he could tell Muffet anything and she'd keep the secret. She called it a 'Spider Silk Secret' which meant she never let it loose. It was funny really. And Papyrus loved to play with her pet, they were so lovable.

He sat at the counter. She skated over. "The usual please" he sighed. Shifting. She quickly retrieved the alcohol and Papyrus went to town. 

Hours later he's drunk as Fuck and begins to walk home. Shifting around; he leaves and stumbled home. Walking in. Sans was sitting on the couch, looking over.

"Oh papy!! Are you drunk?" 

"Nnnh--noo....yes...maybe...yes" he closed the door, sans stood, signing and leading pap to the couch, sitting him down. 

It was a whole second of fine happiness when suddenly sans reached for the others pants."wOAH--bro s-sToP!" He was a bit too drunk to push him away as he hem of his shorts were quickly shoved down. Papyrus tried to move away.

Sans moved, easily shoving the others hands together and cuffing them. "I'm sorry papyrus. I didn't want you to be drunk for our first time but I'm so impatient"

"F-first time?" Papyrus whined, jolting as sans ripped the boxers off. His ungloved hands moving to rub at the tallers pelvis. He whined. Hips trembling. He was so so drunk. The pleasure was so good but so wrong as his member formed.

Sans gasped. "Wowie!! It's so big papy. I'm just gonna suck ya off. Then I'll have our REAL first time later!!"

Papyrus tried to move away. To whine. To scream. But all he could let out was a drunken moans and some awkward trying to shuffle away; which only made the problem worse. Sans's mouth moving around the others cock.  
\---  
(SANS'S POV)

He didn't want Papyrus to be drunk. But he knew it was the only way right now! Later he'd be sober. But for now a simple drunk blowjob would be _so_ good. 

Sans moved around him brother. Easily taking the whole thing into his mouth. Purring as he teased his head with his wet tongue. He had practiced so often. He moaned around him. 

His brother made whined confused moans. Bucking into his mouth drunkingly. "G-this is w-wroonAag sans stoop!!" He begged. But sans didn't end.

He loved the feeling. Bobbing his head up and down faster, his beautiful older brother trying to pull away. Hands trying to Come unbinds. "StOoaaaaaPP~~!!" He came. So fast. He licked up everything as the member vanished. Papyrus weak enough to be moved. He stood. His brother had tears in his eyes and drool leaking down his chin. Sans moved forward and Lapped it up.

"You taste like whiskey~"  
That was his Sans's favorite alcohol. 

He easily carried his squirming taller brother. But it was to no used. Sans might be tiny but he's not weak. He easily kicks his door open. Being careful not to mess up the rose heart. He puts his brother down. Strapping him to the chair.

He takes out a plate of cookies. Forcing his now sobbing brother to eat them. Wiping his tears. "They're drugged. Just sleep papyrus. I'll take good c a r e of you--"

Papyrus passed out.


End file.
